Martin's score could have been even better as he failed to get up-and-down from a greenside bunker at the par-five 18th and had to settle for a closing par.

But he had no complaints after carding his best score on Tour by three strokes.

"The ball was going where I was looking and it seemed like the putts were falling in just like I was seeing them," Martin said.

His score is the lowest on the Tour since Australian Adam Scott also carded a 62 in the opening round of the Arnold Palmer Invitational at Bay Hill in Florida last month.

Martin's hot round was not exactly a bolt from the blue, but rather a continuation of the fine form he displayed at the Heritage in his home state of South Carolina last week.

He was in the hunt deep into the final round there until he made a mess of the 15th hole and eventually finished equal third.

The 26-year-old is in his second season on the PGA Tour. After struggling in his rookie campaign in 2012, he was relegated to the secondary circuit last year, where he won twice to earn another crack at the big time.

While Martin is trying to prove himself at the highest level, Swede Hanson is seeking to regain the form that saw him ranked 19th in the world at the end of 2012, before a back injury that sidelined him for two months last year.

"I know all about what Tiger's going through," said Hanson, referring to Tiger Woods, who last month underwent back surgery and is not expected to return to competition until the summer.

"I'm trying to play a little more relaxed. I managed to make a few putts going out and then had a bit of a jackpot coming in with a two on a really tough hole."

Hanson eagled the par-four sixth, where he holed a six-iron from 183 yards.

Former world number one David Duval also had a good day, posting 68 in just his fourth start of the year.

The 2001 British Open champion, who is not fully exempt on tour, has had trouble securing invitations to play this year.

"I feel I am playing well enough to compete and win golf tournaments," said the 42-year-old, who is not guaranteed another tournament start until Memphis in June.

"I've been working on my swing for a long time, for over a year now, and I feel like it's fixed. I hit the ball pretty much where I was aiming all day."

(Reporting By Andrew Both in Cary, North Carolina; Editing by Peter Rutherford)